The present invention relates to a central heating apparatus comprising a boiler and an oil burner with, interposed between the burner and the boiler walls, a detachable, flame-permeable structure consisting of juxtaposed elements coupled through fastening means to a support having a base portion bearing upon the floor of the boiler furnace, this structure being adapted to be heated white hot in order to improve the combustion and therefore reduce the release of smoke and soot deposits in the furnace.